Difference and Distinction Between Polar and Nonpolar Compounds, Electronegativity, Identification of Polar Bonds

The electronegativity of molecules determines their polarity and nonpolarity. The theory of electronegativity is present throughout inorganic chemistry. The more electronegative an atom, the more electrons it seeks. If one atom is more electronegative than the others, an ionic bond or a polar covalent bond can occur. An ionic link is formed when a significant electronegative atom entirely absorbs an electron from another molecule. If the atom just pulls the electrons towards itself, a polar covalent bond is formed. As a result of the divergent sharing of electrons, the bond has a partly positive and negative end.

Identification of Polar and Nonpolar Bonds

As previously stated, there are two sorts of bonds that can exist: totally polar or entirely nonpolar. Nonpolar covalent bonds exist when there is no difference in the electronegativities of molecules. Polar ionic bonds, on the other hand, are created when the more electronegative atom draws an electron from the other atom.

But what happens in the space between these two extremes?

In terms of electronegativity, bond identification is represented in the table below:

The main explanation for this is the difference in electronegativity between polar and nonpolar bonds.

Polar vs. nonpolar:

A molecule may have polar covalent bonds, but it is not always a polar compound. Because of the presence of a net dipole in a polar compound, they are asymmetrically arranged. Consider water, which is a polar molecule. They have a partly positive charge that cannot be cancelled.

Non-polar compounds, on the other hand, can either share whole electrons or have symmetrical polar bonds that can balance out some form of net dipole. Consider Boron Trifluoride, where the polar bonds are organised in a single plane and end up cancelling each other out. While distinguishing both compounds, a tabular representation is provided below:

Distinction Between Polar and Nonpolar Compounds:

To comprehend the difference between polar and nonpolar compounds, focus on the Lewis structure. Non-polar compounds will be symmetric, which means they will have identical atoms surrounding the central atom, which will link to the element without any unshared pairs of electrons. Because of its tetrahedral shape, the CCl4 molecule is totally non-polar.
Polar compounds are asymmetric in nature as compared to non-polar compounds because they include lone pairs of electrons on a central atom and the connected atoms have various electronegativities. Hydrogen Fluoride (HF), for example, is a diatomic molecule with one side that is slightly positive and the other side that is slightly negative. Because of this difference in electronegativity, it is a polar molecule. It is a polar covalent bond.

The Fluorine atom's strong electronegativity pulls all of the positive charges from the H atom. This is why the H atom has a partial positive charge and the F atom has a partial negative charge. Because of the uneven distribution of electron density, the whole molecule is termed a dipole molecule.

Another important factor to consider when differentiating polar and nonpolar compounds is molecular geometry. The graph below shows a comparison between water and carbon monoxide. Because of the CO2 molecule's linear form, the greater electronegative oxygen atoms pull charges from the carbon atom, resulting in two separate dipoles pointing outward from the carbon atom to the oxygen atom. As a result, the dipoles cancel each other out, and CO2 molecular polarity becomes zero. CO2 is a molecule that is not polar.

Water, on the other hand, has a bent structure, and due to oxygen's stronger electronegativity, it draws out the charges, causing the direct to be H to O. The dipoles cannot cancel each other out because of this structure, therefore the compound is polar. This is the molecular geometry that influences polarity. Because of its linear shape, CO2 has no dipole moment and hence becomes a nonpolar molecule. Water, on the other hand, is a polar compound due to its bent structure, and its dipole moment cannot reach zero.

The primary distinction between polar and nonpolar solvents is that polar solvents dissolve in polar compounds, whereas nonpolar solvents dissolve in nonpolar compounds. Furthermore, polar solvents include molecules with polar bonds, whereas nonpolar solvents contain molecules with similar electronegativity values.